The class of polymers of carbon monoxide and olefin(s) has been known for some time. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical initiators, e.g., peroxy compounds. U.K. No. 1,081,304 produced similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium as catalyst. Nozaki extended the process to produce linear alternating polymers through the use of arylphosphine complexes of palladium moieties and certain inert solvents. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, now conventionally known as polyketones or polyketone polymers, has become of greater interest in part because of the greater availability of the polymers. The more recent general processes for the production of the polyketone polymers are illustrated by a number of published European Patent Applications including Nos. 121,965, 181,014, 222,454 and 257,663. The process generally involves the use of a catalyst composition formed from a compound of a Group VIII metal selected from palladium, cobalt or nickel, the anion of a non-hydrohalogenic acid having a pKa below about 6, preferably below 2, and a bidentate ligand of phosphorus, arsenic or antimony.
The resulting polymers are relatively high molecular weight materials having established utility as premium thermoplastics in the production of shaped articles such as containers for food and drink produced by methods conventional for the processing of thermoplastics.
Although the polyketone polymers are crystalline and have well defined melting points, they do to some extent undergo loss of such crystallinity upon repeated melting/solidification cycles. It would be of advantage to provide compositions comprising the linear alternating polymers which demonstrate improved retention of crystallinity.